Endoscopic procedures such as arthroscopy, hysteroscopy and laparoscopy are well known for examination and treatment of internal areas of the body. Often a seal is formed in a cannula passed through a body wall and medical devices which may be viewing or treating devices, as for example, telescopes and surgical cutting devices, respectively, can be used by passage through the seal in the body cavity. In some cases, no seal is necessary, but a seal is useful in those cases where a body fluid or gas, which may naturally occur in the body or be introduced into the body, is required to be sealed from the outside.
In laparoscopy, a medical device such as a telescope is passed through the umbilicus into a distended abdomen. This procedure is commonly used for diagnosis and therapeutic procedures. The abdomen is distended by filling the peritoneal space with carbon dioxide to separate the tissue from the organs and provide space to view the organs. Such distention of the abdomen is known as pneumoperitoneum.
The telescope placed into the abdomen is put through a cannula which can be a steel, aluminum, fiberglass or plastic tube with a seal of some sort on the proximal end to prevent loss of gas during the procedure. Very commonly, additional puncture sites are made in the abdomen to allow the passage of an assortment of tools. These secondary cannulas have an assortment of seals at their respective proximal ends to prevent the loss of gas during the procedure.
Seals available for these cannula in the past have often been rubber caps that have circular openings that work only when the instrument is in place, filling the hole or requiring the surgeon or nurse to keep their fingers over the open hole. There are some prior art devices that have both rubber caps and hinged ball valves in combination, eliminating the need for the finger approach. Sliding trumpet valves that are pushed open when an instrument is passed through and stays open because of the instrument have also been used.
More recently, disposable cannulas that have both a rubber cap seal, as well as a flapper valve, have been used as a new approach to a sliding valve allowing sliding of the instrument in use.
In all cases, in laparoscopy and other endoscopic procedures, it is important not to let the distention media such as air or CO.sub.2 which has been added, escape from the abdomen or other body cavity. In other procedures where saline or other body fluids must be sealed, it is important to prevent escape of such liquids.
It is also an advantage to be able to utilize a reducer for enabling a predetermined size seal or valve in a laparoscopic cannula to be adapted for use with a smaller diameter or different cross section medical instrument than the original seal was designed for. Thus, various reducing devices have been used for valves of laparoscopic cannula.